© 2011 The McGraw-Hill Companies, Inc. Instructor name Class Title, Term/Semester, Year Institution Introductory Psychology Concepts Hearing

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 2 Hearing  Transduction of sound waves The waves produced by different stimuli are transmitted—usually through the air — in different patterns, with lower frequencies indicated by fewer peaks and valleys per second. (Source: Seeley, Stephens, & Tate, 2000.) Lower frequency (lower pitch) Higher frequency (higher pitch)

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 3 Hearing  Sound: pitch (frequency); loudness and timbre (purity) Auditory stimuli. Sound waves are a form of mechanical energy. As the tuning fork vibrates, it produces successive waves of compression and expansion of air molecules. The number of maximum compressions per second is its frequency, measured in hertz (Hz). The height of the wave above zero air pressure represents the sound’s amplitude. Frequency determines pitch, amplitude determines loudness, measured in decibels (dB). Low pitchHigh pitch SoftLoud Frequency (Hz) determines pitch (tone) Amplitude determines intensity (loudness) (dB)

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 4 Hearing  Parts of the ear A cross section of the ear shows the structures that transmit sound waves from the auditory canal to the cochlea. Tympanic membrane (eardrum) External auditory canal Ossicles Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Auditory vestibular nerves (to brain) Cochlea Oval window Round window Vestibular sacs Auditory tube

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 5 Hearing  Parts of the ear Sound waves travel into an auditory canal leading to the eardrum, a membrane that vibrates in response to the sound waves. Tympanic membrane (eardrum) Ossicles Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Auditory vestibular nerves (to brain) Cochlea Oval window Round window Vestibular sacs Auditory tube External auditory canal

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 6 Hearing  Parts of the ear Beyond the eardrum is the middle ear, a cavity housing the three smallest bones in the body: the hammer, anvil, and stirrup. The vibrating activity of these bones amplifies the sound waves more than 30 times. Ossicles Tympanic membrane (eardrum) Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Auditory vestibular nerves (to brain) Cochlea Oval window Round window Vestibular sacs Auditory tube External auditory canal

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 7 Hearing  Parts of the ear The stirrup (stapes) is attached to the oval window, a membrane which forms the boundary between the middle ear and the inner ear. Ossicles Tympanic membrane (eardrum) Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Auditory vestibular nerves (to brain) Cochlea Oval window Round window Vestibular sacs Auditory tube External auditory canal

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 8 Hearing  Parts of the ear The inner ear contains the cochlea, a snail- shaped tube about 1.4 inches in length that is filled with fluid and vibrates in response to sound. Ossicles Tympanic membrane (eardrum) Malleus (hammer) Incus (anvil) Stapes (stirrup) Semicircular canals Auditory vestibular nerves (to brain) Cochlea Oval window Round window Vestibular sacs Auditory tube External auditory canal

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 9 Hearing  Parts of the ear : inside the cochlea In the cochlea, sound waves are translated into fluid waves that stimulate hair cells in the organ of corti. Scala vestibuli Vestibular membrane Tectorial membrane Scala media (cochlear duct) Organ of Corti Hair cells Basilar membrane Scala tympani Auditory nerve

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 10 Hearing  Parts of the ear : inside the cochlea In the cochlea, sound waves are translated into fluid waves that stimulate hair cells in the organ of corti. The resulting impulses reach the brain via the auditory nerve. Scala vestibuli Vestibular membrane Tectorial membrane Scala media (cochlear duct) Scala tympani Auditory nerve Organ of Corti Hair cells

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 11 Hearing  Perception of Sound Place theory of pitch perception: The specific point in the cochlea where the fluid wave peaks and most strongly bends the hair cells serves as a frequency coding cue. Varying frequencies stimulate different areas of the basilar membrane. High-frequency waves peak quickly and stimulate the membrane close to the oval window.

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 12 Hearing  Perception of Sound Frequency Theory of Pitch Perception: Nerve impulses sent to the brain match the frequency of the sound wave. Both Frequency and Place Theories are applicable in their own ways. At low frequencies: Frequency Theory best explains sound wave frequency coding.  At higher frequencies: Place Theory best explains the frequency of a sound wave coding.

© 2011 The McGraw-Hill Companies, Inc. Introductory Psychology Concepts : Hearing 13 Hearing  In the United States alone, more than 20 million people suffer from impaired hearing. They suffer from two major types of hearing loss:  Conduction Hearing Impairment Problems with the mechanical system that transmits sound waves to the cochlea  Nerve and Hearing Impairment caused by: Damaged inner ear receptors or Damage to the auditory nerve itself